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Solar energy-based hybrid renewable energy generators are techno-economically designed for various standalone uses such as far-distance area electrification, commerical building electrification, polygeneration, and industrial application. This article attempts to address the problem of high cost of energy of such generators, which needs to be optimized. The research gap is that there is hardly any work on techno-economic optimization of such generators using an initial sizing technique, thereby resulting in a design with higher cost of energy. In this work, a hybrid renewable energy generator comprising solar photovoltaic-biogas-battery storage is techno-economically optimized with the aim of minimizing its cost of energy for electrification of a radio-broadcasting station in India by using simulation software called hybrid optimization model for electric renewables. An initial sizing strategy has been proposed in the modeling of the hybrid system. Optimal designs are obtained under different scenarios like in the standalone mode with and without capacity shortage fraction and in grid-connected mode with scheduled and random outages. The results show that during initial sizing in the standalone mode, consideration of larger size (25 kW) of the component with lower unit capacity cost (biogas unit) and higher load sharing by it (102,625 kWh/year) in the energy management of the hybrid design with a small capacity shortage (5%) reduces the levelized cost of energy to 0.0956 $/kWh compared to some of the literature designs. Of all the optimal designs, the grid-connected system has the lowest levelized cost of energy of 0.0873 $/kWh with a renewable fraction of 0.821. The present work contributes to the component size planning of hybrid renewable energy generator to generate lower levelized cost of energy. The novelty of the present work is that in the component size planning in the standalone mode, following the initial sizing strategy, if the component with lower unit capacity cost shares majority of the load, then the levelized cost of energy with or without grid-connected mode can be further reduced compared to some existing designs, which can be verified from the simulation results. Therefore, the present results will be useful for component planning and sizing of hybrid renewable generators so as to preset the size of its components as per their unit capacity cost to result in a lower cost of energy.

Development of hybrid renewable energy system has become a challenging task considering the intermittencies of renewables and multi-dimensional designing aspects (for example technical and economic aspects) of such hybrid systems. Although there are many investigations on the development of hybrid renewable energy systems, the investigations of useful models or effective methods are only a few. Metaheuristic algorithms are gaining much popularity in the optimization of complex systems like hybrid renewable energy system for their ability to give quick, accurate, and optimal solution. The objective of the present study is to obtain a techno-economic optimal design of an off-grid hybrid solar photovoltaic/biogas generator/pumped hydro energy storage/battery system with the help of metaheuristic optimization techniques for a radio transmitter station in India. Performances of two such techniques – water cycle algorithm and moth-flame optimization that have become popular in recent time are evaluated and compared with Genetic Algorithm, which was used as a benchmark metaheuristic in previous studies on hybrid renewable energy system. The objective function is a minimization of total net present cost subject to design constraints. A detailed modeling strategy has been elaborated for the optimization problem. A sensitivity analysis based on loss of load probability type reliability criteria is carried out to investigate the feasibility of the proposed design. The results show that both the considered metaheuristics are effective in finding the optimal design; however, water cycle algorithm has marginally better design solution than the other two algorithms. The optimal configuration by the water cycle algorithm is found to have solar photovoltaic panel area of 548.67 m2 (size 69.2 kW), biogas generator size of 16 kW, battery bank of 21 units, converter size of 30 kW, and upper reservoir volume of 2081.5 m3 with a total net present cost of $0.813 million. Further, on comparing the results with literature, it is found that the present metaheuristic optimization has resulted in an effective hybrid renewable energy system design with a lower techno-economic cost.

The inevitable growth of energy consumption leads to increase in the use of fossil fuel for energy production which ultimately threatens the climate and the health of human being. In contrast, renewable energy does not pollute the environment or produce greenhouse gases. Hybrid Renewable Energy System is one of the eco-friendly power generating system, which normalizes the supply demand mismatch that occurs in a single renewable energy producing unit. The presence of various components in the Hybrid Renewable Energy System makes the designing a bit complex. The objective of this paper is to discuss the various designing parameters and methodologies used for modelling Hybrid Renewable Energy system.